import java.util.HashMap;
import java.util.Map;

public class num617 {
    //合并二叉树
    public TreeNode mergeTrees(TreeNode root1, TreeNode root2) {
        if(root1 == null && root2 == null){
            return null;
        }
        if(root1 != null && root2 == null){
            return root1;
        }
        if(root1 == null && root2 != null){
            return root2;
        }
        TreeNode noed = new TreeNode(root1.val + root2.val);
        noed.left = mergeTrees(root1.left,root2.left);
        noed.right = mergeTrees(root1.right,root2.right);
        return noed;
    }
}
